This invention relates to the use and handling of pipe and tubing in various well operations. More specifically, the invention relates to the use of pipe and tubing and the like being handled with tubing injectors in drilling and well servicing operations.
Jointed pipe or tubing are typically run into wells during well drilling or servicing operations using either a drilling rig or a workover rig. Such rigs can be expensive and time consuming to use. To help minimize some problems in the time and expense of using jointed piped or tubing in well drilling and well servicing operations coiled tubing has been used in its place on a selective basis. Typically, coiled tubing has been used in well servicing operations where time and convenience are important considerations.
In such coiled tubing use, the coiled tubing used has been of the small diameter type where the nominal bore of the coiled tubing is approximately one-inch. The use of such small diameter tubing has occurred in well servicing operations in an effort to provide the maximum amount of tubing mounted on reels that are easily transported over the road on conventionally licensed vehicles to and from well sites. Also, the small diameter coiled tubing may be conveniently transported in reel form installed on skid units to remote locations and offshore. However, such small diameter coiled tubing limits the flow of fluids therethrough, the amount of compression force that can be transmitted through the string of coiled tubing in the well, the amount of tension force that can be transmitted through the string of coiled tubing in the well, the amount of torque that may be applied to the coiled tubing during use in a well, the types of tools that may be used on coiled tubing in a well, the weight of tools that may be used on the string of coiled tubing in the well at any depth, and the length of coiled tubing that may be used in any well.
With the advent of using coiled tubing in a wider variety of well servicing operations and well drilling operations it is desirable and necessary to use larger diameter coiled tubing than in the past, such as three and one-half inches external diameter or greater as may be available from time to time. However, the use of such larger diameter coiled tubing creates a series of problems when coiled tubing handling apparatus designed for handling the small diameter coiled tubing exists is used.
Conventional coiled tubing handling equipment for handling small diameter coiled tubing typically comprises, in simplest form, a reel of coiled tubing mounted on a platform, such as a vehicle, an injector including an integrally attached gooseneck to run the coiled tubing into and from the well, a lifting device to support the injector when running the coiled tubing into and from the well, a power pack to provide power to the reel, to reel the tubing in the well, lifting device to support the injector, the injector to run the coiled tubing into and from the well, and surface equipment to seal around the coiled tubing as it is run into and from the well, such as strippers and/or blow-out preventors.
The vehicle is typically a trailer, pulled by a tractor, upon which the coiled tubing and accessories are mounted to be transported to a well site. Alternatively, a skid unit may be used in place of a vehicle trailer. A hydraulically powered reel is used to run the string of coiled tubing into and from the well. The reel may be of various sizes depending upon the size of the coiled tubing to be reeled thereupon, the length of coiled tubing to be reeled, the size limits of the vehicle for over the road transport, the weight limits for vehicular transport over the road, etc. The lifting device used to support the coiled tubing is typically a hydraulically powered boom or crane which is located at the rear of the trailer so that it may be located adjacent the well and its surface equipment for supporting the injector and gooseneck thereover during coiled tubing operations. The injector having an integrally attached gooseneck is hydraulically powered comprising drive chains having fixed geometry tubing grippers located thereon mounted on beams to run the coiled tubing into and from the well. The integrally mounted gooseneck on the injector typically comprises a curved member, forming a small radius bend having an approximately ninety degree (90.degree.) arc, or less, for directing the coiled tubing between the drive chains of the injector after the tubing has been received, generally horizontally or at a slight angle, from the reel. The gooseneck further includes a plurality of pairs of roller assemblies for the coiled tubing rest upon while being directed by the gooseneck into the injector. The power pack comprises one or more engines driving one or more hydraulic pumps to power the reel, boom or crane, injector, and any surface equipment desired. The power pack may also be used to provide power to any other hydraulic accessory desired.
Since the gooseneck is permanently attached to the injector, the injector must be suspended from the hydraulic boom over the surface equipment of the well at the well site requiring the assembly and disassembly of equipment to be run into the well to occur after the coiled tubing has been run through the gooseneck and the injector. This creates a difficult and sometimes hazardous working environment at the well site in a confined area surrounded by well service equipment.
In some instances, if in addition to coiled tubing, it is required to use jointed pipe, casing, or tubing to be included in the work string used in the well, it will be necessary to use a jack-up frame and power tongs in addition to the normal completion equipment used in coiled tubing operations. In such instances, the injector having an integrally mounted gooseneck thereon will be mounted above the work deck of the jack-up frame for the coiled tubing use. This necessitates the removal of the injector and gooseneck during any operations not utilizing the running of the coiled tubing into and from the well as the jointed pipe, casing or tubing cannot be run through the injector as the grippers of the injector are designed to handle solely coiled tubing of a predetermined external diameter which cannot be varied without changing the grippers on the drive chains of the injector.
In order to improve the efficiency of all types of well drilling and servicing operations it is desirable to use and run pipe, coiled tubing, casing and tubing into and from a well using the same equipment. To do so an injector must be used along with associated equipment that is capable of handling drill pipe of various diameters, coiled tubing of various diameters, well casing of various diameters and tubing of various diameters. Additionally, the equipment used to handle such pipe, coiled tubing, casing, and tubing must occupy the smallest possible space at the well site and be easily transported thereto and therefrom. On-land, offshore, and remote well sites must be considered when using such equipment.
In using coiled tubing it is also desirable to minimize the amount of bending and permanent deformation of the tubing during its use to help prevent fatigue failure of the tubing. When large diameter coiled tubing is used with equipment which is designed to handle smaller diameter coiled tubing, such use may only cause greater bending and permanent deformation of the tubing and its subsequent early fatigue failure because the large diameter tubing is being reeled, supported, and run into a well under the same conditions as smaller diameter coiled tubing which normally utilizes equipment employing smaller reel diameters, smaller radius of bending and support, etc.
It is known to use a mechanism to raise and lower pipe while providing a means for rotating the pipe. Such a device is shown in U.S. Pat. No. 3,191,450.
It is also known to use an injector for injecting coupled pipe into a well using a pair of endless chains to hold the pipe therebetween during running operations. Such an injector is described in U.S. Pat. No. 3,285,485. However, the high loads of squeezing of the pipe between the pair of endless chains tends to deform the pipe couplings making it difficult to disassemble the pipe and reuse it.
It is further well known to use an injector to run coiled tubing to support the tubing without the use of a derrick. Such an injector is shown in U.S. Pat. No. 3,331,346.
It is known to use an apparatus similar to a coiled tubing injector to run sucker rods into and from a well. Such an apparatus is shown in U.S. Pat. No. 3,559,905.
It is also known to use an apparatus to make up a pipe string continuously as it is being run into and from a well. Such an apparatus is shown in U.S. Pat. No. 3,677,345.
It is further known to use gripper pads on drive chains in a sucker rod injector apparatus. Such an apparatus is shown in U.S. Pat. No. 3,754,474.
It is further known to use injectors having movable rails and endless chain drives to allow the use of coiled tubing or jointed pipe to be run through the injectors without the use of a derrick at the well site. Such an apparatus is shown in U.S. Pat. No. 4,655,291, which shows an injector with a pair of chains, each of which is mounted on a rail or pressure beam which is transversely movable with respect to the injector housing.